G-d instructed Moses to tell the people to take a bundle of hyssop and with it apply some of the blood of the Passover animal to the lintel and the two doorposts
The right doorpost signified good deeds; the left doorpost signified prayer,
and the lintel above them signified the study of the Torah. Together, these
three constitute a complete, balanced life that enables us to fulfill our Divine mission of making the world into G-d’s home.
The door itself signified our readiness to obey G-d’s will, since this
commitment is the entrance into our active partnership with G-d to rectify
the world. The lowly hyssop used to apply the blood to the doorframe
signified the self-abnegation we must cultivate in order to be receptive to
G-d’s presence in our lives. The blood itself signified the vitality of our animating soul, with which we must perform good deeds, pray, and study
Every personal exodus from an “Egypt” requires that we humbly apply our vitality to action, prayer, and study of the Torah, all performed with renewed commitment to our Divine mission in life.
—from Daily Wisdom #1